The present invention relates to a system using solar energy for electrical generation and the engine and other parts of the system.
Since the price of fossil fuels, especially petroleum and natural gas, began to rise, there has been increased demand for solar technology to replace the energy of burning fossil fuel. Most of the applications use the solar energy for heat, primarily space heating or heating water for hot water and swimming pools.
Much of the energy consumed in this country is electrical energy, but technology in harnessing solar energy to produce electricity has lagged behind using solar energy for heat. Solar energy is being used to generate electricity in two fields. The first relates to photovoltaic systems. Presently, the photovoltaic systems are extremely costly, and only in remote, lowpower consumption uses such as satellites or highway warning signs are they cost justified.
The other approach for solar electrical generation uses solar energy to replace the energy of burning fossil fuel or the energy of a nuclear reactor for heating a fluid in a turbogenerator. Solar energy is used to boil water to convert it to steam to drive a turbine which in turn drives a generator. Thereafter, the fluid is condensed and pumped back into the boiler where the cycle continues. This cycle, the Rankine cycle, is typical for power plants.
Although there have been proposals to develop relatively small solar power plants, much of the research has been directed to large solar generators that would replace relatively large coal or other fuel burnings electrical generators, such as the 10 MW generator that is being built in the Mojave Desert near Barstow, California. The project involves a large number of mirrors mounted on the ground which reflect solar energy at a boiler mounted on a tall tower. The boiler operates conventionally and steam is delivered through pipes to a turbogenerator.
There are many drawbacks to the system. First, the boiler is mounted on a tall tower, and there is a substantial heat loss through the long pipes leading from the boiler to the turbine. Sabotage is another concern. One could easily shoot a high powered rifle bullet through length of exposed tubing, and the high pressure steam would explode through the hole.
There is also another drawback to the large systems. Such systems would either be run by a governmental unit or an electrical utility which means regulated pricing. Smaller systems for use of an industrial facility, a commercial building, a farm or an apartment house or condominiums can eliminate the need of a large regulated utility and of having the government in the power business. This system proposed herein would even be applicable to a single family house, but it is believed that the power from one such system could be shared by a number of houses.
Although the efficiency of a turbogenerator tends to increase as the size increases, small systems eliminate other inefficiencies of large-scale power systems. For example, transformers and overhead and underground wires would be eliminated. Decreased labor costs would also accrue. No billing personnel such as meter readers and billing clerks would be necessary. Even the costs of mailing bills and payments would be eliminated.
If on-site solar electrical generation replaces only a portion of the users electrical needs, price rises by a utility will affect the consumer less.
One of the objects of the present invention is to disclose and provide a small solar electrical generator of a high efficiency so that a single unit could be used by a single electrical user such as an industrial plant, a commercial facility, a farm, a residence or a group of residences.
Efficiency of a Rankine engine increases as the pressure increases and the steam temperature at the turbine increases. Therefore, efficient utilization of solar energy can greatly increase the efficiency of the turbogenerator. However, in traditional tubular or flat plate heat transfer surfaces, heat transfer is extremely inefficient. It may be necessary, therefore, in order to have the same temperature and pressure to use a prohibitively large solar collector. Another object, therefore, of the present invention is to disclose and provide an extremely efficient boiler. Tubular and flat plate boilers also heat unevenly. The portion to which the heat is applied expands more than the rest of the walls of the boiler. This uneven expansion and contraction can weaken the boiler. Even if it does not cause the boiler to fail, the weakening is taken into account in designing boilers, and they must be made thicker. Another object of the present invention is to disclose and provide a boiler that has uniform heating of the boiler walls and that exchanges the heat from the boiler to the working fluid efficiently.
Along with efficient heat transfer within the boiler, it is important that the solar collectors use solar radiation efficiently and transfer the solar energy to the boiler. To do so, it is important that the minimum amount of energy is reflected off the boiler. It is an object of the present invention to minimize energy transfer losses.
Another object of the present invention is to disclose and provide a condenser of increased efficiency for use in the present system.
Another object of the present invention is to disclose and provide a system which eliminates or decreases many of the inefficiencies caused in large-scale power plants. If the turbine is located a great distance from the boiler, there may be a substantial pressure drop due to frictional effects of the pipe if the boiler is far from the turbine. Heat is also transferred through long pipes. A large pump may be needed to pump the water from the condenser to the boiler. Another object of the present invention is to eliminate or substantially decrease inefficiencies in the pump itself.
These and other objects will become evident from the foregoing description.